Nowadays, due to the advent of the Internet, information, such as data, graphics, video or text, are easily transmitted and shared across devices operating on different platforms, for example, personal computers (PCs), notebook computers, personal digital assistants (PDAs) and mobile phones.
As these devices are designed for different applications, it is not surprising that these devices all have different requirements and limitations, such as size of the display, memory capacity, available processing power and power consumption.
Now, a number of these device limitations affect how information is presented.
For example, how to present, say, a photograph which fills a large display screen (say, of a desktop PC) on a relatively small display screen (say, of a mobile phone) without any visible loss in visual quality, is a problem, in view of such a large diversity of devices.
There are currently two commonly used methods of representing graphics, namely, the raster based representation and the vector based representation.
In the raster based representation, each pixel is defined separately, for example, as in a digital photograph. As such, raster based representations are typically used in representing digital photographic images. Examples of raster based representations include the Graphic Interchange Format (GIF) format and the Joint Photographic Experts Group (JPEG) format.
The GIF format only allows the use of 256 colors, which is often insufficient for high quality photographic images. Accordingly, the GIF format is rarely used for high quality photographic images (the JPEG format is typically used for this application). However, the GIF format has an advantage in that it employs a lossless data compression technique. Therefore, with the GIF format, it is possible to reduce the size of a digital image without any loss in visual quality.
In a vector based representation of a digital picture, lines are represented using mathematical formula are used to draw lines (for example, taking two points and draw a parabola between them), which are then interpreted at the receiving side to produce and display the graphic. Because of this, with vector based representations sharp graphics may be provided using smaller files compared to raster based representations. However, with vector based representations, the process of rendering and displaying complex graphics is slower due to the large amount of processing required.
Vector based representations are typically used for desktop PC, Internet and mobile applications. Examples of vector based representations include the Flash format and the Scalable Vector Graphics (SVG) format.
The Flash format means the format used by the Adobe Flash Player and a multimedia authoring application program used to create content for Internet applications, computer games and movies. The Adobe Flash Player is a client side application widely available in most Internet browsers, which supports both the raster and vector based graphics representations. The use of vector based graphics representation in Flash format files (or .swf files), in combination with some program code, allows the size of Flash format files to be smaller than equivalent bitmap files or video clip files.
The SVG format is an XML-based text file format. Like the Flash files, the size of the SVG format files is also relatively small, when compared to the raster based representation formats. Another advantage of the SVG format is its scalability, meaning that the client side limitations can be used to determine how the file is rendered or displayed, by controlling parameters such as resolution, transformation and so on.
In this regard, it is noted that the size of files obtained using the vector based representations is generally smaller than those obtained using the raster based representations. Additionally, in the context of file sharing and transmission, a smaller file size is advantageous in that the said file requires less bandwidth for its transmission across wired or wireless networks.
Despite the advantages of all the above discussed graphics representation formats, the size of files obtained using these formats may still be relatively large.